package me.chanjar.weixin.common.util;

import java.security.AlgorithmParameters;
import java.security.InvalidAlgorithmParameterException;
import java.security.Key;
import java.security.NoSuchProviderException;
import java.security.Security;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import org.bouncycastle.jce.provider.BouncyCastleProvider;

public class AESUtil {
  public static boolean initialized = false;

  static {
    Security.addProvider(new BouncyCastleProvider());
  }

  /**
   * AES解密
   * 
   * @param content
   *          密文
   * @return
   * @throws InvalidAlgorithmParameterException
   * @throws NoSuchProviderException
   */
  public byte[] decrypt(byte[] content, byte[] keyByte, byte[] ivByte) throws Exception {
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
    Key sKeySpec = new SecretKeySpec(keyByte, "AES");

    cipher.init(Cipher.DECRYPT_MODE, sKeySpec, generateIV(ivByte));// 初始化
    byte[] result = cipher.doFinal(content);
    return result;
  }

  // 生成iv
  public static AlgorithmParameters generateIV(byte[] iv) throws Exception {
    AlgorithmParameters params = AlgorithmParameters.getInstance("AES");
    params.init(new IvParameterSpec(iv));
    return params;
  }
}